William boy moot



WILLIAM ROY MOTT, OF LAKEWOOD, OHIO, ASSIGNOB TO NATIONAL CARBON COMPANY,

INC., A CORPORATION OF. NEW YORK.

ARC-LAMP ELECTRODE.

No Drawing.

To all whom it may concern Be it known that I, WILLIAM R. Morr, a

citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Arc-Lamp Electrodes, of which the following is a full, clear, and exact description. g I This invention relates particularly to improvements in arc lamp electrodes although the phenomena disclosed may be utilized in electrodes for other purposes.

The object of the invention is to obtain an artificial source of light of high intrinsic brilliancy and increased candle power.

Another object of the invention is to se cure an intensely brilliant source of light approximating a point source which is the ideal illumination for projector arc lamps and searchlights.

The positive crater of the carbon arc has always been supposed to have the highest intrinsic 'brillia-ncy of any source of light, and is also the nearest approximation to-a. point source of light of high candle'power. The highest temperatures readily obtainable heretofore for various investigations also are found in the positive crater of the carbon are. 4

I have found new means by which it is possible to secure an intensely bright ositive crater which is of much eater rilliancy than the carbon are an also has a higher are temperature.

The materials which have been found to produce this result are metallic tantalum and certain tantalum compounds, particularly the oxid and carbi'd. These materials are preferably embodied either alone or combined with other flaming materials, in the core of a positive carbon electrode, or as a wire in thec'enter of the electrode. The

combination of tantalum, and zirconium is especiallygood. A carbon shell containing about 50% ofzirconium oxid gave the most steady arc. The crom section of the core or the diameter of the wire may be varied sizes are preferably about the same as those of the ordinary open arc. flame cored carbons. The negative is "preferably carbon althoug an electrode containing flaming material may be used. It has previously been believed and reported that the carbon is depending on the result desired, but the in the literature Specification of Letters Patent. Patented July 22, 1919. Application filed October 2, 1918. Serial N0. 256,600.

that all flaming materials decrease the arc and crater temperatures of the carbon arc, but I have found that tantalum increases the arc temperature and is a marked exception to this rule. on burning an electrode having tantalum incorporated therein, this phenomena is evidenced by the unique fact pitted at the points where the arc strikes the tantalum, very probably because the tantalum has been raised to such a high temperature that the carbon below it has. been volatilized. The very concentrated at the point where the arc rests on the tantalum and the candle power of the arc as a whole is considerably increased by the very small intensely brilliant crater.

A current of at least 6 amperes, and preferably 20 to 50 amperes, is desirable to best develop the small, very bright, White incandescent positive crater. The light is whiter than that obtained in lowen' temperature carbon arcs, principally because the temperature is higher.

In investigations with the arc spectrum, the increased temperature attainable may be a means of decidedly modifying the spectrum previously obtained with the carbon arc.

Having described my invention, What I claim is:

1. An. electrode containing carbon and tantalum.

2. A positive electrode containing carbon and tantalum material.

3. An electrode containing carbon and hail'ing a core containing'a'tantalum mater1a 4. A positive electrode containing carbon and a core of metallic-tantalum.

5. In arc lamps, the combination of a positive electrode containing tantalum and a negative electrode containing carbon.

6. An electrode containing carbon, tantalum and zirconium.

7. A positive electrode containing carbon and zirconium and having a core containing tantalum.

8. A positive electrode containing carbon and zirconium oxid and having a core containing a tantalum material.

In testimony whereof, I hereunto aflix my signature.

WM. ROY MOTT. 

